Section 2A. In determining the qualifications necessary for registration as a qualified physician, the board may at its discretion accept the certificate of the National Board of Medical Examiners of the United States, chartered under the laws of the District of Columbia, or the certificate of the National Board of Examiners for Osteopathic Physicians and Surgeons of the American Osteopathic Association, in place of and as equivalent to its own professional examination; but before registration in pursuance of this section the applicant therefor shall pay a fee to be determined annually by the commissioner of administration under the provision of section three B of chapter seven.